The Transformation of Nitrogen in Paddy Soil under Different Climatic Conditions and Different Chemical Fertilizers.
Kyeong-Bo Lee1, Chan-Won Park2, Deog-Bae Lee3, and Jae-Duk Kim2. (1) Honam Agricultural Research Institute, NICS, RDA, 381 Songhak-dong, Iksan, 570-080, South Korea, (2) Honam Agricultural Research Institute NICS, RDA, 381 Songhakdong, Iksan, 570-080, South Korea, (3) National Institute of Agricultural Science Technology, RDA, Suwon, 441-707, South Korea
The increasing of greenhouse gases may change agricultural environment. The agronomic productivity will depend upon change of temperature, precipitation, solar radiation and fertilization. Particularly, nitrogen fertilization and temperature considerably influence rice productivity and agricultural environments. Therefore, how to increase N use efficiency and to reduce the N negative impacts is essential to find out harmonious agriculture with environment. This experiment was conducted to study transformation of nitrogen in paddy soil under different climatic conditions. NH4-N in surface water was main form of N, and increased rapidly after fertilizer applied in four treatments, which in order as NPK>LCU70>LCU50>PK, and then was decreased sharply due to rice absorption and loss to environment. NO3-N concentration in surface water was very low. NH3 volatilization is important way for N loss in paddy soil, and rate and accumulation of NH3 volatilization increase with concentration of NH4-N in surface water increased. The accumulation of NH3 volatilization in NPK treatment was 43.21kgN/ha, which accounted for 39.28% of fertilizer N applied but using of LCU fertilizer can reduce NH3 volatilization by 64% in paddy soil of subtropical area. Use efficiency of N fertilizer was not different between LCU70 and LCU50 treatment. Rate of N use efficiency were 29.5%, 46.8%, 48.2% in paddy field of temperate zone NPK, LCU70, LCU50 treatments respectively, on the other hand rate of N use efficiency in paddy field of subtropical zone low was about 10% than that in paddy field of temperate zone. The yield of LCU70 showed the best effect with 21~27% increase production ratio, compared with PK treatment.